The conventional means for forming relief patterns on a synthetic resin film and paper includes the use of an embossing roll. However, the relief patterns by use of the embossing roll are small in depth and liable to wear out and the patterned sheet cannot be glossy at both side surfaces.
Also, there is another method for forming the relief patterns on a synthetic resin sheet by use of printing ink blended with a foaming agent, which has the problem that foaming portions are formed on the surface to weaken strength of the sheet and a transparent product cannot be obtained.